With the rapid development of wireless communication technology, user requirements have grown. In order to meet the growing user requirements on the large volume and high quality data communication, multi-antenna technology using two or more antennas is adopted.
In the case of using two or more antennas (antenna elements), i.e. an antenna array, if the antennas are connected to respective Analog to Digital (A/D) converters, there is no problem of splitting the signals received via the antennas. However, since the A/D converter or a device responsible for the similar function is expensive part, it is advantageous to reduce the number of A/D converters used for processing signal as far as possible from the view point of cost effectiveness. Furthermore, reducing the number of A/D convertors is also advantageous in reducing the power consumption and heat and conserving space for internal components.
In the convention technology in which a plurality antenna and other signaling components are connected to one digital path, i.e. one A/D converter, the same signal is received several times. In this case, the intended signals are split by applying different post-processing algorithms to the same signal received repeatedly.
FIG. 1 illustrates the signal split algorithm.
Referring to FIG. 1, the signal reception apparatus includes a first antenna 101, a second antenna 102, a first phase shifter 103, a second phase shifter 104, a summer 105, and an A/D converter 106. The first antenna 101 is connected to the first phase shifter 103, and the second antenna 102 is connected to the second phase shifter 104.
It is assumed that the first antenna 101 receives signal x1 and the second antenna 102 receives signal x2. The signal reception apparatus receive the same signal twice. The signal reception apparatus applies phase values of orthogonal unitary code to the phase shifters 103 and 104 in receiving the signals.
The first phase shifter 103 multiplies the phase w1 to the signal received via the first antenna 101 in receiving the signal x1, and the second phase shifter 104 multiplies the phase w2 to the signal received via second antenna 102 in receiving the signal x2 first. The phase-shifted signals are summed at the summer 105 and the summed signal is converted to the digital signal by the A/D converter 106. The result signal is expressed as y1=x1w1+x2w2.
Equation (1) shows the relationship between the aforementioned signals and phases.
                                          [                                                                                w                    1                                                                                        w                    2                                                                                                                    v                    1                                                                                        v                    2                                                                        ]                    ⁡                      [                                                                                x                    1                                                                                                                    x                    2                                                                        ]                          =                  [                                                                      y                  1                                                                                                      y                  2                                                              ]                                    (        1        )            
Equation (1) can be modified into equation (2).
                              [                                                                      x                  1                                                                                                      x                  2                                                              ]                =                                            [                                                                                          w                      1                                                                                                  w                      2                                                                                                                                  v                      1                                                                                                  v                      2                                                                                  ]                        H                    ⁡                      [                                                                                y                    1                                                                                                                    y                    2                                                                        ]                                              (        2        )            
Using equation (2), it is possible to split the signals x1 and x2 received via the two antennas 101 and 102 using the output signals y1 and y2 and the phase shift values w1, w2, v1, and v2.
However, the conventional method has a drawback in that the same signal has to be received twice or more times. Also, the conventional method has a drawback in that the repetitive reception of the same signal delays splitting the signal.